Electronic devices and method of making same



y 25, 1965 e. A. GRANITSAS 3,185,555

ELECTRONIC DEVICES AND METHOD OF MAKING SAME Filed May 18, 1960 IIIQIIIEIIIIIIIIIIII] GEORGE H. GEHNLTSHS F) T TOBN'EYS United States Patent "ice 3,185,555 ELECTRONIC DEVICES AND METHOD OF MAKING SAME George A. Granitsas, Marlboro, Mass, assiguor to American Optical Company, ,Southbridge, Mass, a voluntary association of Massachusetts Filed May 18, 1960, Ser. No. 29,909 3 Claims. (Cl. 65-18) The field of this invention is that of electronic devices and the invention relates, morepar-ticular-ly, to a novel and improved electron image read-out or storage device and to a novel and advantageous method of manufacturing such a device.

An electronic device of the type with which this invention is concerned comprises a sheet or disc embodying a multiplicity of electrical conductors which extend between faces of the sheet in spaced, side-by-side relation within a matrix of an insulating material, the ends of each conductor being exposed from the matrix material. These devices are adapted to receive and to transmit or retain an electron pattern or image projected upon one face thereof by various means and are adapted to be scanned or otherwise sensed for reading out the charge image projected thereon. Such an electronic device is useful, for example, in xerographic printing wherein the device is incorporated within a cathode'ray tube to form the face plate of the tube, the electron gun of the tube being adapted to project an electron charge image upon one face of the device inconventional manner. In this application, the device conductors are adapted to transmit the charge image to the other face of the device to produce a corresponding electrostatic charge image upon a paper tape or similar means disposed against said other device face. The electronic device can also be utilized in conjunction With conductors leading away from such a cathode-ray tube face platefor exciting magnetic means to transfer a charge image projected upon the face plate to a magnetic tape. As will be readily understood, resolution of the charge image retained or transmitted by such an electronic device is enhanced by the uniformity of conductor size and spacing therein and by the multiplicity of conductors within each surface area of the device.

It is an object of this invention to provide a novel and improved electronic device of the character described which is adapted to accomplish maximal electron image resolution; to provide such a device having similarlysized, electrically conductive members uniformly spaced within an insulating matrix; and to provide such a device in which the conductors will be satisfactorily secured within said matrix. It is a further object of this invention to provide a novel and advantageous method of making an electronic device of the type described; and to provide such a method by which such devices can be inexpensively and conveniently manufactured.

Briefly described, the electronic device provided by this invention comprises a multiplicity of similarly-sized grains or pellets of electrically conductive material which are uniformly spaced in side-by-side relation within an insulating matrix for forming a disc or sheet. Within the disc or sheet, which preferably has substantially parallel faces, each conductor extends between opposite faces of the disc or sheet, the conductors having end surfaces of corresponding diameter exposed in the plane of each disc face for providing surfaces to be electronically scanned, and each having a portion of larger diameter embedded in the matrix material intermediate the disc faces for securing the conductors therein.

According to this invention the method by which such devices can be conveniently and inexpensively manufactured includes the steps of assembling a multiplicity of Patented May 25, 1965 similarly-sized grains or pellets of electrically-conductive material in side-by-side relation within a single layer, preferably by disposing the grains or pellet-s upon a plate and by vibrating the plate to spread the grains or pellets in a single, loosely-packed layer. Thereafter the layer is covered wtih an insulating matrix material for coating the pellets and for filling interstices of the layer thereby to bond the pellets together in the form of a sheet or disc in Which the pellets are uniformly spaced in side-by-side relation. For example, the assembled layer of pellets can be covered with powdered glass or plastic which can be heated for melting the glass or plastic to coat each of the pellets, and thereafter the glass can be permitted to cool for bonding the pellets together. Then the disc is supported, for example by alternately adhering faces of the disc to a supporting block, and the unadhered faces are abraded in conventional manner for providing smooth faces on the disc and for providing a flat, exposed surface on each side of each of the pellets within the plane of the disc faces, thereby to provide surfaces to be electronically scanned.

Other objects and advantages of the device and method provided by this invention appear in the following more detailed description which refers to the drawings wherein:

FIG. 1 diagrammatically illustrates the initial steps in the method provided by this invention;

FIG. 2 diagrammatically illustrates subsequent steps in said method;

FIGS. 3 and 4 diagrammatically illustrate the final steps in said method;

FIG. 5 is a plan view of the electronic device provided by this invention;

FIG. 6 is a section view along line 66 of FIG. 5; and

FIG. 7 is a diagrammatic view illustrating use of the electronic device provided by this invention.

Referring to the drawings, 10 in FIG. 1 indicates as fiat plate or pan which is adapted to receive a multiplicity of similarly-sized grains or pellets 12 of copper, silver, aluminum or other suitable, electrically-conductive material. According to this invention, the pellets or grains are disposed upon the plate 10 and the plate is vibrated,

as indicated by the arrow 10a in FIG. 1,until the pellets have spread out to form a single, loosely-packed layer. Thereafter, as shown in FIG. 2, an insulating material 14 such as glass or plastic, preferably in powdered form, is applied to the layer of pellets for covering the pellets and for filling interstices of the layer. Then, as indicated by the heater coils 13 in FIG. 2, the glass or other insulating material 14 is heated to the melting point for completely coating each one of the pellets 12, thereby to space the pellets uniformly within said layer. If necessary, further vibration of the plate 10 can be provided for assuring that each pellet is completely coated with the insulating material. It should be understood that although the insulating material is most advantageously applied to the assembled layer of pellets in the manner described, glass or other insulating material such as various plastics could be applied to an assembled layer of pellets in melted form or could be melted and mixed with the pellets for coating the pellets before the pellets are assembled in a layer Within the scope of this invention.

After the pellets in the layer have been properly coated and spaced, the insulating material spacing the pellets is permitted to cool or set for bonding the pellets in said spaced relation to form a disc or sheet 16. Preferably the insulating material has a coefficient of thermal expansion corresponding to that of the pellets so that expansion and contraction of the sheet 16 resulting from temperature changes occurring during use of the device provided by this invention will not cause separation of the bond between the pellets and the insulating matrix.

When the insulating material has cooled or set, the sheet 16 is removed from the pan 10 and is mounted upon a supporting block 18 or other suitable means by use of an adhesive 26 or the like. Then the surface 16.1 of the sheet which faces away from the supporting block is abraded, for example by use of the grinding wheel 22 as shown in FIG. 3, for exposing one side of each of the pellets 12 from within the matrix and for providing each of the pellets with a flattened surface 12.1 which falls within the plane of the sheet surface 16.1, thereby to provide the disc with a smooth face to be electronically scanned. After abrasion of the disc face 16.1, the disc is removed from its supporting block in conventional manner and is remounted in reversed position for permitting corresponding abrasion of the disc face 16.2 as shown in FIG. 4, thereby to smooth the face 16.2 and to provide flattened, exposed surfaces 12.2 on each of the pellets.

The electronic device 16 prepared by the above-described process is illustrated in FIGS. 5 and 6 and, as shown, comprises a multiplicity of electrically conductive members 12 which are uniformly sized and spaced within a matrix 14 of an insulating material, the conductors extending between opposite faces, 16.1 and 16.2, of the device and having surfaces 12.1 and 12.2 of corresponding area or diameter exposed in the plane of the disc faces for providing scanning surfaces thereon. As shown particularly in FIG. 6, each conductive member 12 has a portion indicated by the arrow 12.3 which is of larger diameter or cross-sectional area than the conductive member faces 12.1 and 12.2, this portion being embedded in the matrix material intermediate the device faces 16.1 and 16.2 for securing the conductive member therein.

The electronic device 16 is adapted to receive an electron image or pattern upon one face thereof and to transmit or retain a charge image with high image resolution as a result of the uniformity of conductor size and spacing and as a result of the multiplicity of conductors utilized in transmitting or retaining the image. As shown in FIG. 7, the electronic device is particularly useful in xerographic printing when incorporated in an otherwise conventional cathode-ray tube 24 to form the face plate of the tube, the device being fused or otherwise secured to the tube envelope 24.1. The cathode-ray tube is provided with a conventional electron gun 24.2 and with conventional electron beam deflecting means 24.3 and is adapted to project an electron image or pattern upon the surface 16.1 of the device 16 in accordance with a signal received by the tube in conventional manner. Rolls 26 are mounted adjacent the tube face plate for supporting a paper tape 28 or other suitable means against the face plate, the tape 28 being adapted to receive and retain an electrostatic charge image as is customary in the xerographic printing process. As will be readily understood, the conductors 12 in the device 16 are adapted to transmit the electron image projected upon the face 16.1 to the device face 16.2 to produce such a negative electrostatic charge image upon the tape. Thereafter, the tape can be advanced through a quantity of positively charged powdered ink particles (not shown) for reproducing the charge image with ink particles, or the tape can be otherwise treated for permanently recording the charge image upon the tape.

Although particular applications and embodiments of the method and device provided by this invention have been described for the purpose of illustration, it should be understood that this invention includes all modifications and equivalents thereof which fall within the scope of the appended claims.

Having described my invention, I claim:

1. The method of making an electronic device of the character described which comprises as steps: providing a multiplicity of similarly-sized balls of electrically-conductive material having a predetermined coefiicient of thermal expansion; disposing the balls on a substantially flat-bottomed pan; vibrating the pan for spreading the balls in a single, loosely-packed layer on said pan bottom; covering the layer of balls with powdered glass insulating material having a coefficient of thermal expansion corresponding to that of said balls; heating the glass material for fusing said material to coat the balls and to fill interstices of the layer of balls; permitting the fused glass material to cool for bonding the coated balls together in uniformly spaced relation within the layer to form a sheet; and abrading opposite sides of the sheet for determining sheet thickness and for providing corresponding flattened, exposed surfaces on each ball at respective opposite sides of the ball center in the plane of each of said sides so that each of said exposed surfaces is of smaller diameter than the diameter of said ball, thereby to securely hold each ball within said glass materials and to provide scanning surfaces on the opposite ends of each ball.

2. The method of making an electronic device of the character described which comprises as steps: providing a multiplicity of similarly-sized balls of electrically-conductive material; providing a hardenable insulating material adapted for coating the balls; assembling the balls in a single layer with a coating of said insulating material on each ball for spacing the balls substantially uniformly from each other Within said layer; hardening the insulating material for forming a matrix holding the balls in said spaced relation; and abrading opposite sides of said layer for exposing a segment of each ball at each side of said layer which is flush With the layer side and which is of smaller diameter than the diameter of said ball; whereby each ball can serve as an insulated conductor leading between said layer sides but can be securely held within the matrix material.

3. The method of making an electronic device of the character described which comprises as steps: providing a multiplicity of similarly-sized balls of electrically-conductive material; assembling the balls in sidc-by-side relation to each other in a single layer; applying a hardenable insulating material to the layer of balls for filling interstices between the balls and for coating the balls to space the balls substantially uniformly from each other within the layer; hardening the insulating material for forming a matrix holding the balls in said spaced relation; and abrading opposite sides of said layer for ex posing a segment of each ball at respective opposite sides of the ball center at each side of said layer so that each said segment is flush with the side of the layer and is of smaller diameter than the diameter of said ball; whereby each ball can serve as an insulated conductor leading between said layer sides but can be securely held within the matrix material.

References Cited by the Examiner UNITED STATES PATENTS 2,189,340 2/40 Donal 2925.14 2,345,278 3/44 Monack 43 2,568,126 9/51 Keeley 156-298 2,646,364 7/53 Porth l56240 2,885,826 5/59 Grieve 65-32 2,955,385 10/60 McDuffee 6532 2,963,606 12/60 Crews 3l373 2,992,956 7/61 Bazinet 65-35 DONALL H. SYLVESTER, Primary Examiner. RALPH G. NILSON, Examiner. 

1. THE METHOD OF MAKING AN ELECTRONIC DEVICE OF THE CHARACTER DESCRIBED WHICH COMPRISES AS STEPS: PROVIDING A MULTIPLICITY OF SIMILARALY-SIZED BALLS OF ELECTRICALLY-CONDUCTIVE MATERIAL HAVING A PREDETERMINED COEFFICIENT OF THERMAL EXPANSION; DISPOSING THE BALLS ON A SUBSTANTIALLY FLAT-BOTTOMED PAN; VIBRATING THE PAN FOR SPREADING THE BALLS IN A SINGLE, LOOSELY-PACKED LAYER ON SAID PAN BOTTOM; COVERING THE LAYER OF BALLS WITH POWDERED GLASS INSULATING MATERIAL HAVING A COEFFICIENT OF THERMAL EXPANSION CORRESPONDING TO THAT OF SAID BALLS; HEATING THE GLASS MATERIAL FOR FUSING SAID MATERIAL TO COAT THE BALLS AND TO FILL INTERSTICES OF THE LAYER OF BALLS; PERMITTING THE FUSED GLASS MATERIAL TO COOL FOR BONDING THE COATED BALLS TOGETHER IN UNIFORMLY SPACED RELATION WITHIN THE LAYER TO FORM A SHEET; AND ABRADING OPPOSITE SIDES OF THE SHEET FOR DETERMINING SHEET THICKNESS AND FOR PROVIDING CORRESPONDING FLATTENED, EXPOSED SURFACES ON EACH BALL AT RESPECTIVE OPPOSITE SIDES OF THE BALL CENTER IN THE PLANE OF EACH OF SAID SIDES SO THAT EACH OF SAID EXPOSED SURFACES IS OF SMALLER DIAMETER THAN THE DIAMETER OF SAID BALL, THEREBY TO SECURELY HOLD EACH BALL WITHIN SAID GLASS MATERIALS AND TO PROVIDE SCANNING SURFACES ON THE OPPOSITE ENDS OF EACH BALL. 